Streptococcus gordonii LuxS/autoinducer-2 quorum-sensing system modulates the dual-species biofilm formation with Streptococcus mutans

Abstract

Dental plaques are mixed-species biofilms that are related to the development of dental caries. Streptococcus mutans (S. mutans) is an important cariogenic bacterium that forms mixed-species biofilms with Streptococcus gordonii (S. gordonii), an early colonizer of the tooth surface. The LuxS/autoinducer-2(AI-2) quorum sensing system is involved in the regulation of mixed-species biofilms, and AI-2 is proposed as a universal signal for the interaction between bacterial species. In this work, a S. gordonii luxS deficient strain was constructed to investigate the effect of the S. gordonii luxS gene on dual-species biofilm formed by S. mutans and S. gordonii. In addition, AI-2 was synthesized in vitro by incubating recombinant LuxS and Pfs enzymes of S. gordonii together. The effect of AI-2 on S. mutans single-species biofilm formation and cariogenic virulence gene expression were also assessed. The results showed that luxS disruption in S. gordonii altered dual-species biofilm formation, architecture, and composition, as well as the susceptibility to chlorhexidine. And the in vitro synthesized AI-2 had a concentration-dependent effect on S. mutans biofilm formation and virulence gene expression. These findings indicate that LuxS/AI-2 quorum-sensing system of S. gordonii plays a role in regulating the dual-species biofilm formation with S. mutans.

Quorum sensing LuxS/autoinducer-2 inhibits Enterococcus faecalis biofilm formation ability

“…Above all, the LuxS gene may be involved in the attachment and aggregation of bacteria during the biofilm formation and may be the key gene that controls biofilm formation of E. faecalis. Previous studies by other authors revealed that LuxS/AI-2 could down-regulate metabolism-related enzymes of E. faecalis through proteomics analysis and speculated AI-2 signaling plays an important role in the regulation of a number of important metabolic properties of E. faecalis and even played essential roles in other oral bacteria 25 , such as Streptococcus mutans, Escherichia coli, Porphyromonas and Actinobacillus 14 , 18 , 19 , 22 ; these results are consistent with our study.…”

“…In addition, the synthesis of AI-2 relays on the LuxS gene. In oral studies, the LuxS gene in Streptococcus mutans, which is related to cariology, has been previously clarified 19 , but the role of the LuxS gene in E. faecalis, the main pathogen of PAP, still has not been elucidated. To investigate the LuxS gene function, we built a LuxS gene knockout strain and detected the role of LuxS gene in biofilm formation directly by comparing its biofilm formation ability with the standard strain.…”

“…Recently, the LuxS gene-mediated quorum sensing (AI-2 signaling) was found to plays an important role in interspecies communication and has been involved in bacterial virulence, persistence infections and biofilms formation in bacteria, such as Streptococcus mutans, Escherichia coli, and Actinobacillus . 14 , 18 , 19 Nevertheless, the relation between the LuxS gene expression levels and the biofilm formation ability of the pathogenic bacteria E. faecalis remains unknown.…”

Effect of cAMP Receptor Protein Gene on Growth Characteristics and Stress Resistance of Haemophilus parasuis Serovar 5

“…Finally, the cells were incubated at 37 • C for 24-48 h. To verify the construction results of the crp mutant, the UKD sequence, kanamycin resistance cassette gene, and crp gene were amplified and then verified by sequencing. The growth characteristics of the wild-type and crp mutant strains were measured (Wang et al, 2017;Zhang et al, 2019). The wild-type and crp mutant strains were cultured in 5 ml fresh T/V/S medium overnight and then diluted with the same medium until the OD 600 value had reached 0.4.…”

Biofilms and their properties

“…In a more recent study, Wang and coworkers showed that AI‐2 communication was important for dual biofilm of S. mutans and S. gordonii . Furthermore, inactivation of the luxS gene (and consequent failure to produce AI‐2) leads to increased sensitivity to chlorhexidine .…”